1. Technical Field
The present invention relates to a gas thruster assembly for producing a predetermined quantum of impulse for attitude control of vehicles such as satellites, missiles, spacecraft, and the like. More particularly, the present invention relates to an apparatus for selectively delivering either of two levels of impulse or thrust upon command and if desired in a repetitive fashion.
2. Background Art
Various propulsion systems, discused below and incorporated herein by reference, have been proposed for controlling the attitude or relative positions of a vehicle.
For example, Stratton (U.S. Pat. No. 4,258,546) describes a propulsion system for use in spin-stabilized vehicles including a liquid or fluid-fueled rocket engine having a thrust chamber, a differential area piston dividing the thrust chamber into a charging chamber and a combustion chamber. This system utilizes the spin forces of the vehicle or a propellant expulsion system for delivering fuel from a storage container to the charging chamber and means for initiating movement of the piston to drive fuel from the charging chamber to a combustion chamber.
As noted in Turansky et al (U.S. Pat. No. 4,428,188), control of a space vehicle along three mutually orthogonal axes is realized by utilizing a bistable valve arrangement which may feed, sequentilly, two opposite directed thrusters. This is accomplished by providing an electromagnetically functioned valve assembly.
A quantitized impulse rocket is described by Horner (U.S. Pat. No. 3,088,406). Specifically, the Horner impulse rocket is designed to precisely inject a predetermined amount of fuel into a combustion chamber which is independent of the thrust generated by the rocket. This is accomplished by utilizing an injection pump including a piston assembly having dual solenoid valves which when activated allows the injection of the entire amount of predetermined quantities fo fuel and oxidizer stored within the injector pump cylinder into the combustion chamber.